At the heart of a comer's coma lies a nucleus of solid material, typically no more than 10 kilometers across.- G! i& N& Q' n5 Z
The word "heart" is closest in meaning to which of following?- }7 n% Z! G; d4 M B# c
(A) center
. o( ]' l. M8 J- b(B) edge
% u2 P& ]% R/ o- L" Q8 [6 j(C) tail
3 F5 c3 H @0 A, Y(D) beginning
6 s1 c. S4 I: ^ I4 E# t4 a" v5 m% q1 f0 }8 ^
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.8 t% F1 G$ x, k! c% ?6 }
The word "graphic" is closest in meaning to which of following?. m8 t) B' C7 Q" v3 ]2 d2 S9 | K
(A) mathematical
& j9 U! q" n' K# l [$ l3 K(B) popular
# Y! E: ^& O' ]" y0 K1 n(C) unusual1 L! \) C6 B y: y. K
(D) vivid; w9 D. ]. w* r0 J9 E4 g- U6 Q
: L- t4 q* L3 y) a403. As a comet's orbit brings it closer to the Sun, first the coma grows, then two distinct tails usually form.) m) n/ k1 l5 t0 ` |8 T5 L
The word "distinct" is closest in meaning to which of following?# T5 G# h! G9 U0 h" p, y
(A) visible
: h/ U" V8 E. o. A& r(B) gaseous2 x( d, T% u5 q f: W" B
(C) separate
R4 v9 X5 n% C; ^& e(D) new! @) E9 m! w& p8 ?# N
1 O4 V; z5 ]6 [/ I; b. Pheromones are substances that serve as chemical signals between members of the same species. g) r9 X" g% I$ x' ~
The word "serve" is closest in meaning to which of following?
+ \3 i( L7 T8 _7 ?. I F8 G8 }(A) improve
, ^& @2 Z9 p+ E1 f, a% R% n; _8 `(B) function8 t* {- O: M3 O- P9 H
(C) begin$ o, @5 f! r) v& ]
(D) rely. n8 O* p: u1 e
0 R: E4 P/ E* r; f+ s6 Z* l. 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. m3 ~6 b) R0 ?4 L# \6 E0 m
The word "sole" is closest in meaning to which of following?5 ]/ P3 X; G5 J% o, j+ e% [
(A) obvious
* Y& m" `% a. z5 Y" S(B) best2 c/ x0 c `& Y5 a: w% Z( \! Q5 a6 ?
(C) only0 t) |$ H( g1 l
(D) final" ?/ b3 R( ^9 E0 J# i
ADCBC |
发表于 2012-8-14 22:41:43
