20. When he entered the back yard, the farmer caught a boy _____ his apples.

A steal　　　 B to steal　　 C stole　　 D stealing

19. It is no use ______ about it. You can’t do anything to change it.

A. to worry 　 B. worried　　 C. worrying　　 D. worries

18.　 I can never forget the day _______ we worked together and the day________ we spent together.

A. when, which　 　 B.which, when C. what, what　　　 D. on which, when

17. We had a picnic last term and it was a lot of fun, so let’s have______ one this month.

A. the other 　 B. some　 　 C. another　 　 D. other

16. More and more young people are fond _______ playing tennis nowadays.

A. of　　 　 B. on 　　C. in　 　 D. with

(听力用英语周报上的题)

20、(10分)已知数列{a_n}满足a₁＝1，a_n＞0，S_n是数列{a_n}的前n项和，对任意n∈N*，

　有2S_n＝2a_n²+a_n－1

　(1)计算a₂，a₃的值，并求数列{a_n}的通项公式　

　(2)求满足S_m≤27的m的最大值　　　

(3)记b_n＝(n∈N*)，求证：

19、(12分)如图,　 P为菱形ABCD所在平面外一点,M、N 分别为AD、PB 的中点，平面PAD⊥平面ABCD,PA=PD=AD=2,∠DAB=60⁰

求证： (1)MN //平面PCD(2)AD⊥PB　 (3)求三棱锥D-PBC的体积

18、(6分)已知圆C：，求过点A(2，4)与圆相切的直线方程

17、(6分)在锐角△ABC中，a、b、c分别为角A、B、C所对的边，且

(Ⅰ)确定角C的大小：　 　

(Ⅱ)若c＝,且△ABC的面积为,求a+b的值。