--You should have thanked her before you left.
--I meant ________, but when I was leaving I couldn’t find her anywhere.
| A．to do | B．to | C．doing | D．doing so |
These diagrams are especially helpful when we have a concrete problem ______ at hand.
| A．be solved | B．to solve | C．solved | D．being solved |
This kind of gel pen which ______ smoothly is quite popular with students.
| A．is written | B．is writing | C．wrote | D．writes |
It is the bus driver who should ______ the safety of the passengers.
| A．answer for | B．search for | C．stand for | D．go for |
I’m very grateful to my high school teachers, without ______ help I wouldn’t be so excellent.
| A．whom | B．their | C．which | D．whose |
I ______ for Shanghai this Saturday, so I want to know when the earliest plane ______.
| A．leave; takes off | B．am leaving; takes off |
| C．leave; is taking off | D．am leaving; is taking off |