29. On March 12, the students were planting trees ____ the classroom.
| A．in the back of | B．at the back of | C．to the back of | D．on the back of |
I'm __________ in books these days since the finals are coming.
| A．caught | B．buried |
| C．stuck | D．missed |
It is a pity that most slimmers __________ putting weight back on.
| A．ended up | B．brought up |
| C．took up | D．broke up |
Did it __________ to you that he was jealous?
| A．happen | B．occur |
| C．strike | D．take place |
Two middle-aged passengers fell into the sea. __________，neither of them could swim.
| A．happen | B．occur |
| C．Naturally | D．Unfortunately |
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 |