Titan, Saturn's largest moon, has an elliptical rather than a circu-' Y0 Y/ h* h; g: r+ B$ A
lar orbit around that planet. If Titan has one or more oceans, the
4 H# o1 {5 ?, F gravitational pull of Saturn must raise substantial tides on Titan.
6 s+ S5 m6 y9 O8 h' Y* A) p If, as well as having oceans, Titan had one or more continents,7 B0 C+ o4 J! g2 O
the resulting tidal friction would long ago have turned Titan's orbit& r! x& f% Z# C2 `2 X
into a circle.( N) t% A3 y. d4 Z' l' G7 {* h! [7 q
If all of the statements are true, they provide the most support for
( T$ Z2 Y) g. b6 {( owhich of the following conclusions?" A$ l* ~# J( {. C0 K' Q0 W
A Titan has oceans and also has at least one continent. , i- s7 O! ~# o) \ `8 T( I. O
B Titan either has no ocean or else has no continent.
% q [$ K) l/ s% \5 Y0 w) q C Titan is probably considerably older than it was previously9 S2 ?- W! E. S! J+ X
estimated to be. 2 b) s( ]. _* C" x& v4 k
D At some time in the future, the orbit of Titan will probably
% j* V$ H% w1 C$ V: t become circular in shape.
5 B6 k* h" y5 W$ [* M& k; X E At some time in its past, Titan had an orbit that was circular9 g0 a7 u+ J& s0 ]/ M* v" ?
in shape.
! K" ^4 y6 S; i9 G$ ]答案B |
发表于 2012-8-15 12:40:43
