The computer centre, ______ last year, is very popular among the students in this school.
| A．open | B．opening |
| C．having opened | D．Opened |
The students expected there ________ more free time before the test.
| A．is | B．have been | C．to be | D．being |
Does the way you thought of ________ the water clean make any sense?
| A．making | B．to make | C．how to make | D．having made |
The bridge is so important to the people here that once ________ it must be carried out without delay.
| A．designs | B．having designed | C．designing | D．designed |
They tried to prevent the damage ________ their cattle.
| A．from protecting | B．protecting | C．protect | D．to protect |
His father disappeared, ________ two children and never _______ from again.
| A．left; being heard | B．leaving; heard | C．left; be heard | D．leaving; to be heard |