集合的并运算符是______。A．∪ B．OR C．UNIQUE D．UNION

将方程3x（x-1）=5（x+2）化为一元二次方程的一般式______．

用所给词的适当形式填空

小题1:We should prevent fire__________________ (burn) the house at once.

小题2:Please cut out the ___________________ (necessary) words.

小题3:It’s______________ (correct) to drop litter _____________ (care).

小题4:The poor children got back to school_________ (with)the help of the kind people.

小题5:It’s_____________ (excited) for me to pass the driving test.

小题6:I hope this information will help you understand the ________ (important) of study.

小题7:Milk is the ________ (nature) food for young babies.

小题8:Listen! How ___________________ (happy) they are singing and dancing.

小题9:My mother        (cook) when I            (arrive) home yesterday.

小题10:_____ Amy ____ (visit) the Science Museum from 9:00 a.m. to 11:00 a.m. yesterday?

某学生在使用显微镜观察人的口腔上皮细胞时，操作如下：

（1）用一块洁净的纱布擦去镜头上的脏物；

（2）用消毒牙签在漱净的口腔侧壁上轻轻地刮几下，然后涂在滴有一滴清水的载玻片上的水滴中；

（3）放在显微镜载物台正中央，并用弹簧夹片压住；

（4）双眼注视物镜，将物镜降至距玻片标本1～2 cm处停止；

（5）用左眼向目镜里观察，同时转动粗准焦螺旋使镜筒缓缓上升．

请指出该生在以上操作中不正确的地方．

This classroom is __________than that one.[ ]

A. many big        

B. much big

C. many bigger      

D. much bigger

右侧外展神经麻痹，左侧上下肢中枢性偏瘫（）。

A.左侧延髓病变

B.右侧桥脑病变

C.左侧桥脑病变

D.右侧延髓病变

E.左侧中脑病变