Man-made-satellites______ into space by many countries.
| A．was sent up | B．is sent up | C．have been sent up | D．has been sent up |
—Why does the lake smell terrible?
—Because large quantities of water .
| A．have polluted | B．have been polluted |
| C．is being polluted | D．has been polluted |
—Hi, Tom, why are you looking so tired?
—I'm tried. Because I ______ the living room all day.
| A．painted | B．have been painting |
| C．have painted | D．had painted |
__________ is troubling me is __________ I don’t understand __________ he said.
| A．What; that; what | B．It; that; what |
| C．That; that; what | D．what; that; which |
______________________, I would have given you his address.
| A．If you asked me |
| B．You had asked me |
| C．Should you have asked me |
| D．Had you asked me |
As a teacher, he knows exactly how to his ideas to the students.
| A．consult | B．display |
| C．convey | D．comfort |