Not until all the fish died in the river how serious the problem of water pollution was.
| A．did they realize | B．they did realize | C．had they realized | D．they had realized |
The price of _______ bike will partly be determined by the sort of ______ material used.
| A．the; the | B．the; / | C．/; the | D．/; / |
However much money you have, it can not _______ a healthy body.
| A．compare | B．fit | C．defeat | D．match |
This is the first time for him to ______ your beautiful country.
| A．call on | B．pay a visit to | C．drop in | D．come |
I can hardly believe my eyes. What a poor composition you have ______! There are so many wrong spellings in it.
| A．turned into | B．turned off | C．turned to | D．turned in |
The truth, sir, is that the old man _______ across the road when my car hit him.
| A．was to walk | B．had been walking | C．walked | D．was walking |