Trees are useful to man mainly in three ways, the most important of which is that they can protect ______ from droughts (干旱) and floods.
| A．it | B．itself | C．himself | D．him |
Students are always interested in finding out _______ they can go with a new teacher.
| A．how far | B．how soon | C．how often | D．how long |
The last time we had great fun was _____ we were visiting the Water Park.
| A．where | B．how | C．when | D．why |
It is obvious to the students ______ they should get well prepared for their future.
| A．as | B．which | C．whether | D．that |
News came from the school office ________Wang Lin had been admitted to Beijing University.
| A．which | B．what | C．that | D．where |
Could I speak to ______ is in charge of International Sales please?
| A．who | B．what |
| C．whoever | D．whatever |