Scientists photographed for the first time ever _____ wild gorillas used a stick to test the depth of a pool before getting into it, according to a recent study.
| A．which | B．what | C．that | D．when |
A railway station is no place for a child ________ alone at night.
| A．leave | B．leaving |
| C．to be leaving | D．to be left |
With much work ________unsettled，the newlyselected president will have a hard time.
| A．remaining | B．remained | C．remains | D．to remain |
He was sitting on the floor ________ by books.
| A．surrounded | B．surrounding |
| C．surroundings | D．surround |
The weather turned out to be fine yesterday. I ________ the trouble to carry my umbrella with me.
| A．should have taken | B．could have taken |
| C．needn't have taken | D．mustn't have taken |
My father may have to go into hospital，________ he won't be going on holiday.
| A．in that case | B．in which case |
| C．in case | D．in the case |