15. When Madam Curie did the experiment again, she was more careful where she _____ a mistake.
| A．made | B．has made | C．was making | D．had made |
The dark clouds are gathering. You’d better take your umbrella _______ it rains.
| A．when | B．even if | C．if | D．in case |
At the gate _______ two stone lions.
| A．stands | B．stand | C．was stood | D．standing |
It’s hard for a woman to run after fashion as it _______ so quickly.
| A．has changed | B．has been changing | C．was changed | D．is changed |
The twin brothers are very similar ______ appearance but quite different _____ hobbies.
| A．to , in | B．to ,from | C．in ,in | D．in, from |
Children experts suggest children ______ more time to play freely.
| A．are given | B．will be given | C．be given | D．must be given |