Titan, Saturn's largest moon, has an elliptical rather than a circu-
( ^; {& e+ b) |8 q6 v lar orbit around that planet. If Titan has one or more oceans, the5 w, m0 \4 _' b% ^! \% ` k
gravitational pull of Saturn must raise substantial tides on Titan.
' F5 ]/ q9 |' q5 H If, as well as having oceans, Titan had one or more continents,
5 D2 I8 a# E: k; X. u- t9 Q0 k" c% ithe resulting tidal friction would long ago have turned Titan's orbit3 f' Z7 L3 P2 K( d1 F
into a circle.
7 W; K9 U3 G2 f2 ?- ?& g- c" s: Z3 _ If all of the statements are true, they provide the most support for
5 o+ n/ v9 L5 V( ?' s$ K0 iwhich of the following conclusions?
% @; r: {! s qA Titan has oceans and also has at least one continent.
) E* Y' K [* @" e: S& o( u B Titan either has no ocean or else has no continent. P6 J4 ]" f4 h/ `7 r
C Titan is probably considerably older than it was previously0 B" H, m: m3 z _5 ~/ v/ h
estimated to be. # W, u* t. x, q
D At some time in the future, the orbit of Titan will probably U9 g0 ]3 ^% [& j
become circular in shape.
. x+ t! X6 y7 M2 z6 Y& d E At some time in its past, Titan had an orbit that was circular
0 l9 w4 ]9 T# W in shape.
* Z! g# w! c1 Z5 K! i0 u答案B |
发表于 2012-8-15 12:40:43
