It never occurred to humans until the mid-1990s some animals can be cloned.
| A．where | B．that | C．when | D．what |
—You look tired, Jack． What's wrong with you?
—Oh, 1 worked quite late last night． Nothing wrong with me,．
| A．although | B．though | C．yet | D．still |
After climbing the hills in the natural park for hours, my legs _under me and I failed to keep pace with others．
| A．gave out | B．gave up | C．gave in | D．gave away |
Tom told us all that he said so at the meeting was really true．
| A．that | B．all | C．what | D．which |
This ischallenging job I mentioned to you the other day． Have you had anyone inmind for it now?
| A．a, the | B．the;/ | C．the, the | D．a:/ |
In such a background, his white hair was particularlyhis dark skin．
| A．in relation to | B．in need of | C．in contrast to | D．in favor of |