______ the ancient Egyptians built the pyramids puzzled people for centuries.
| A．Whether | B．What | C．How | D．Where |
The laboratory was well ______ for atomic research.
| A．offered | B．equipped | C．provided | D．supplied |
You must ______ a wide vocabulary if you want to learn a language well.
| A．set up | B．put on | C．settle down | D．build up |
Don’t bother Tom, he is ______ with the experiment on water molecules in the lab.
| A．focused | B．fixed | C．occupied | D．concentrated |
Nowadays some parents regret not ______ more time with their kids when they were young.
| A．to spend | B．spending | C．spend | D．being spent |
Have you heard that he, as well as his parents, ______ visited the Summer Palace?
—Really? No ______ he didn’t attend the meeting.
| A．have; doubt | B． has; choice | C．have; reason | D．has; wonder |