What would have happened＿＿＿＿, as far as the river bank?
| A．if Bob has walked farther | B．if Bob should walk farther |
| C．had Bob walked farther | D．if Bob walked farther |
The police ________him to see if he had a gun.
| A．searched | B．searched for | C．in search of | D．looked for |
Is this museum _______some German friends visited the day before yesterday?
| A．which | B．that | C．where | D．the one |
The visitors saw rows of houses the roofs _______are red.
| A．where | B．that | C．what | D．of which |
As is known to all, China _______the group of developing countries.
| A．belonging to | B．was belonged to | C．belongs to | D．is belonged to |
There is no doubt _______international cooperation is the key to dealing with cyber crime.
| A．then | B．that | C． wheather | D．this |