We were having evening class ____ the light went out.
| A．while | B．even if | C．as if | D．when |
Having finished the work, _______.
| A．it was almost six o’clock |
| B．supper was ready |
| C．a postman came and delivered some letters. |
| D．we had a rest and then had supper |
---When was Tom bitten by a snake?
---It was on a Sunday _______ he was taking a trip to the mountainous area.
| A．that | B．when | C．which | D．where. |
When this new kind of virus broke out at first in Mexico, no one had the least idea that it would _______ so rapidly throughout the world.
| A．export | B．spread | C．expand | D．deliver |
---Is the new job a real challenge for him?
---Well, _______ difficulties he meets，I believe he will never lose heart.
| A．however | B．whenever | C．whatever | D．Whichever |
“___________ race” means that two people form a group with their on-leg tied and they will walk for contest with three legs.
| A．three-legging | B．three-legged |
| C．three-legs | D．three-leg |