The doctor the farmer sent his son is well-known in the field.
| A．by whom | B．at whom |
| C．to whom | D．for whom |
I was wondering what to do and＿＿＿＿＿＿Mr. Wang came in.
| A．just | B．just now | C．just then | D．justly |
David jumped＿＿＿to get the first＿＿＿the beginning of the sports.
| A．enough high； in | B．enough highly； in |
| C．high enough； at | D．highly enough； at |
By the time the fire-fighters arrived, the fire had been put＿＿＿by the teachers and the students.
| A．down | B．away | C．out | D．off |
Such a problem is＿＿＿＿difficult for a primary school student ＿＿＿.
| A．so； to work | B．very too； to work out |
| C．rather too； to work out | D．quite too； to answer |
The railway was opened＿＿＿＿＿＿traffic＿＿＿＿＿＿＿ April 4, 1985.
| A．to； on | B．to； in | C．by； on | D．for； on |