When was it _____ your parents took you to Hangzhou?
| A．before | B．if | C．which | D．that |
After five hours’ drive，they reached________they thought was the place they had been dreaming of.
| A．where | B．what |
| C．which | D．that |
Professor Backman took up scientific research for decades，and this is________he devoted all his life to.
| A．which | B．what |
| C．where | D．how |
Sorry I’m so late，but you cannot imagine________great trouble I took to find your house.
| A．what | B．how |
| C．which | D．why |
Water，which seems so simple and common，is________makes life possible.
| A．what | B．that |
| C．which | D．how |
—You know，I’m poor in Chinese，you are not good at English，and...
—That’s________we should help each other.
| A．when | B．where |
| C．how | D．what |