21.Ba missed the Math test yesterday. ___A_____, he will have to do it next week.
A. therefore B. but C. and D. because
22. My sister is very tired: ___B_____, she still has to cook dinner for the family.
A. so B. however C. and D. as
23. She doesn’t look so pretty ____D____.She has soft voice.
A. and B. but C. so D. however
24. They don’t like the opera ____C____ it doesn’t look sound interesting.
A. and B. but C. because D. so
25. Daisy is very nice: ____C____, all her friends love her very much.
A. and B. so C. therefore D. because
26. Can you turn_____A____ the lights? It’s too dark.
A. on B. off C. in D. for
27. What are you looking ____C____? My picture book. I’ve lost it.
A. on B. off C. for D. after
28. There are _____D___ saving methods and inventions to use solar energy.
A. energetic B. energize C. energy D. power
29. I had to pay much money this month for the international____A____.
A. calls B. calling C. to call D. called
30. A new – conditioner will be ____B____ this morning.
A. to install B. installed C. installing D. to install.