21. My flat is near the river. I often stand in the balcony and ________ the boats in the river.
A. look out of B. look out at C. look out from D. look for at
22. --- Would you like to come to my home for supper with me tomorrow?
--- I'd love to ,but ________ a business trip(出差).
A. am going to having B. will having C. am going to have D. am having
23. --- Are these CDs ________? --- No, they are not mine. They belong to________.
A. yours; her B. yours; hers C. your; hers D. yours; she
24. --- Can a plane fly ________ the Pacific Ocean(太平洋) ?
--- Yes, but it needs to go ________ the clouds for hours.
