At the heart of a comer's coma lies a nucleus of solid material, typically no more than 10 kilometers across.. t8 v# ~, p5 @- G& _4 r) q
The word "heart" is closest in meaning to which of following?, K: y* F/ ]; ^& n3 F3 e9 Y; o' W
(A) center
2 \: a+ `9 T9 V8 ^3 A(B) edge1 |, c' W! z8 k# u
(C) tail
; T3 k j+ C' W3 t+ b, Z1 q9 V(D) beginning
J# j9 V4 s% |+ v
- X& [. i) Y; e9 W, E- c The most graphic proof that the grand spectacle of a comet develops from a relatively small and inconspicuous chunk of ice and dust was the close-up image obtained in 1986 by the European Giotto probe of the nucleus of Halley's Comet.4 u' b% |$ K3 B: W" _" S; k
The word "graphic" is closest in meaning to which of following?
" W' t- U; ^9 {1 C4 E7 C }9 I(A) mathematical
! d( ]; k4 {8 ]1 Q4 U2 F(B) popular' A8 m8 c! ?1 d
(C) unusual
b( T7 t- V2 b$ I. q( P(D) vivid+ Y' a8 a3 T6 m/ M# X8 h
6 ?: q h$ O3 R! E
403. As a comet's orbit brings it closer to the Sun, first the coma grows, then two distinct tails usually form." W. f7 I3 }# A: v/ Q! J
The word "distinct" is closest in meaning to which of following?( N! T- f6 i) Y. N! E7 E
(A) visible x1 q, f9 @. \2 G# B" g
(B) gaseous
8 s6 k1 }: g* P* x3 ?1 j4 h- _(C) separate1 o: C1 V7 `, Z. v" M
(D) new' |& b. u. k- n( H# I
2 X( |1 B3 q$ w2 n. N
. Pheromones are substances that serve as chemical signals between members of the same species.2 x5 W* {) |9 q1 V0 }1 {$ S9 e
The word "serve" is closest in meaning to which of following?$ n- d- Z; A' `3 U
(A) improve
2 o3 A$ P9 _' ` K(B) function
" X$ e! g, _! t" W" {# T+ ~(C) begin6 r/ Y2 M- X3 m E; v) N% q
(D) rely
; \0 G- ^5 l/ H* ?6 Y: j$ e
9 I5 a& C* T5 `2 S" ]% z8 H. Pheromones are the predominant medium of communication among insects (but rarely the sole method) . Some species have simple pheromone systems and produce only a few pheromones, but others produce many with various functions.
7 ^! i, ]. C# tThe word "sole" is closest in meaning to which of following?
7 R2 H5 A6 ?* n; Y(A) obvious
5 L k2 ^! c v% Q: X(B) best z, D6 E' D" @, c
(C) only! i& G2 \2 D6 k4 i3 |
(D) final% l6 [" @0 K$ Y# O" r0 e
ADCBC |