(2013·安徽，21)From space, the earth looks blue. This is ________ about seventyone percent of its surface is covered by water.
| A．why | B．how |
| C．because | D．whether |
They said they ______ do some sports if it was fine.
| A．were going to | B．went | C．would going | D．were going |
He ______ in Shanghai University for four years before he ______ Beijing.
| A．studied, had gone | B．had studied, went |
| C．has studied, goes | D．had studied, had gone |
Mary said it was at least five years since he ______ a good drink.
| A．enjoyed | B．was enjoying | C．had enjoyed | D．would enjoy |
Xiao Pei said she ______ Hainan for 3 months.
| A．has been in | B．had been in | C．had been to | D．had gone to |
--What are Mr and Mrs Black doing ?
---They _____ tea in the garden.
| A．are drinking | B．drank | C．have drunk | D．drink |