题目

过点（-1，0）作抛物线y=x2+x+1的切线，则其中一条切线为（    ） A.2x+y+2=0                   B.3x-y+3=0C.x+y+1=0                     D.x-y+1=0 答案：思路分析：y′=2x+1，设切点坐标为(x0,y0)，则切线的斜率为2x0+1，且y0=x02+x0+1,于是切线方程为y-x02-x0-1=(2x0+1)(x-x0),因为点（-1，0）在切线上，可解得x0=0或-2，代入可验证D正确.答案：D根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。 根据对话内容，从对话后的选项中选出能填人空白处的最佳选项，并将答案填写在本题下 面的横线上。选项中有两项为多余选项。 A： Mary, we are going to have a party on New Year's Eve. Fm sure we'll have a good time. 1._____ B： I'd like to. 2._____ A： In our classroom. We are going to decorate it and turn it into a splendid ballroom. B： 3.____ I shall be very glad to spend my first New Year in China with you. A： But we are going to ask everyone at the party to give a performance. 4.____ B： I will. My voice is not very pleasant to the ear, though. A ： I heard you sang once. 5._____ Fm sure you'll be the star of our New Year party. B： Oh, thank you. A．Your voice was sweet and beautiful. B．Where are you going to have it? C．Would you like to join us? D．Thank you for inviting me. E. Oh, it is great. F. Let's go to the ball together. G. Do sing us some English songs, please.