20. The primary purpose of the passage is to
' m: s3 S0 D% @0 b (A) describe the way in which hot spots influence the extinction of volcanoes' P5 [, N6 }' q$ K# J6 v
(B) describe and explain the formation of the oceans and continents/ j& T$ B0 J, a) t
(C) explain how to estimate the age of lava flows from extinct volcanoes
+ q1 s+ q7 O" z (D) describe hot spots and explain how they appear to influence and record the motion of plates
& d" t5 D" Q& J# `" H (E) describe the formation and orientation of island chains in the Pacific Ocean! l% C9 {8 t, j. B+ {5 D4 }
21. According to the passage, hot spots differ from most volcanoes in that hot spots; w; v) o7 ]) e: L
(A) can only be found near islands
5 R+ U! |' E! k4 W5 a, b2 R (B) are active whereas all other volcanoes are extinct
$ K, K/ Z5 _' \( z5 h (C) are situated closer to the earth's surface, f" G) C" Y8 M3 Q& i6 w: k
(D) can be found along the edges of the plates2 d; h( e% v- H) y0 I
(E) have greater amounts of alkali metals in their lavas
2 }& Y6 E) X2 w7 { 22. It can be inferred from the passage that evidence for the apparent course of the Pacific plate has been provided by the
) |: i1 S$ U9 A# ^; Q* D (A) contours of the continents.
) s6 P+ t _3 L9 M( ?2 N (B) dimensions of ocean hot spots, S% O9 s: L2 z$ l2 S% _
(C) concurrent movement of two hot spots3 n- d/ I' o. N! \; y8 ^& { g
(D) pattern of fissures in the ocean floor
* @+ c/ R( E* j* G (E) configurations of several mid-ocean island chains, Q. W+ |3 k }; Z* x
23. It can be inferred from the passage that the spreading out of lavas of different ages at hot spots indicates that a
$ {' r6 J% S! g: x (A) hot spot is active7 r8 U' H' q( K/ Z' Z$ ]* g
(B) continental plate has moved
! O7 g: o& w& i5 g6 [0 I (C) continental rupture is imminent! B" G9 A; j: d5 m# y& r
(D) hot spot had been moving very rapidly
- W7 y* m {% o3 d (E) volcano contains large concentrations of alkali metals
! t: t5 n. x# f/ v1 t5 ` 24. The passage suggests which of the following about the Hawaiian Islands, the Austral Ridge, and the Tuamotu Ridge?6 G _" V- I$ Q9 T* u
(A) The three chains of islands are moving east- ward.4 T& ]% z. V" I
(B) All the islands in the three chains have stopped moving., ^8 l5 z; q/ }, Q& A( A$ ]" c
(C) The three islands chains are a result of the same plate movement.
5 I3 n( H! ]5 K( j- }7 c/ j (D) The Hawaiian Islands are receding from the other two island chains at a relatively rapid rate.$ x0 g( G3 g/ `! T$ C3 e- a, ~
(E) The Austral Ridge and the Tuamotu Ridge chains have moved closer together whereas the Hawaiian Islands have remained stationary./ c& C: K; g& a) X% t; p! n
25. Which of the following, if true, would best support the author's statement that hot-spot activity may explain the mutability of continental plates?
7 _- ~* J3 f. L6 B (A) Hot spots move more rapidly than the continental and oceanic plates.7 r$ ?. l3 Q A$ K0 n
(B) Hot spots are reliable indicators of the age of continental plates.% R1 m+ S+ @3 W% w
(C) Hot spots are regions of volcanic activity found only in the interiors of the continental plates.
! c* s5 X8 i8 ?( W (D) The alignment of hot spots in the Pacific. Ocean parallels the alignment of Pacific Ocean islands.
8 P% z; q# S/ w2 p (E) The coastlines of Africa and South America suggest that they may once have constituted a single continent that ruptured along a line of hot spots.5 u+ e* i" P% g* e
26. The author's argument that hot spots can be used to reconstruct the movement of continental plates is weakened by the fact that
/ a6 B W% @$ D5 y6 T (A) hot spots are never found at the boundaries of plates* X: {: e4 m+ p/ S1 C
(B) only extinct volcanoes remain after a plate moves over a hot spot
8 R) r+ A6 u, n1 n& ` (C) lava flow patterns for all hot spots have not been shown to be the same
. ^5 r. r7 R6 N+ P' C (D) the immobility or near immobility of hot spots has not been conclusively proven, C: G9 A& W& R& |3 x6 n
(E) the changing configurations of islands make pinpointing the locations of hot spots difficult
. `6 [ r* E# W' M 27. The author's style can best be described as+ H! Y# a4 Q' G1 e0 l
(A) dramatic来www.Examw.com
( x/ Y7 {) }; D% J (B) archaic( G l6 G1 `0 A2 q% X7 D" K
(C)esoteric5 K8 `0 H+ L0 r) h3 c, C
(D) objective; C+ M; {% e9 Y' F
(E) humanistic( ` \6 C8 m$ Z( h
28. SUBTLE:. m, `5 R6 J2 v& k. p4 y! c
(A) careful+ c- _' N5 i$ D! U# _: H T7 t
(B) dirty
" e; I5 W3 c5 W9 [7 p N (C) obvious
& H* B+ M' Z7 s2 N (D) intentional
5 O0 K& L0 q8 p9 N (E) eager |