Only when I made it to the train station _______ that I had left my ticket at home.
| A．have I realized | B．did I realize | C．had I realized | D．would I realize |
It was announced that only when the terrible disease was under control _____ to return to their homes.
| A．the residents would decide | B．would the residents decide |
| C．would the residents be decided | D．the residents would be decided |
Spelling Bee is a contest _____ competitors, usually children, are asked to spell as many words as possible.
| A．which | B．where | C．what | D．when |
When asked to explain _____ he did to make his students so fascinated with his lessons, the teacher paused and thought deeply.
| A．what was it that | B．that what it was |
| C．what it was that | D．what was it |
The subway was crowded with passengers going home from market, most of _____ carrying heavy bags and baskets full of fruit and vegetables they had bought there.
| A．whom | B．them | C．who | D．which |
—The research on the new flu virus vaccine is challenging and demanding. Who do you think can do the job?
—______ my students have a try?
| A．May | B．Must | C．Will | D．Shall |