n个顶点的强连通图的邻接矩阵中至少有 个非零元素。 A．n-1 B．n C

造成精制塔釜温低的原因，说法正确的是（）。

A、进料中重组分高

B、回流量小

C、蒸汽凝液罐满

D、进料温度高

It is Ms Chen’s serious attitude________ her work and her interesting methods of teaching that

make us like her very much.

A．with

B．on

C．towards

D．about

根据括号中的汉语提示或用括号内英语单词的适当形式填空。

小题1:_____________, the boy rushed out his room.（突然）

小题2:Li Ping, do you have any good ____________? （主意）

小题3:These years, _____________ food is more and more popular in China.（西方的）

小题4:Beijing is the ____________ of our country.（首都）

小题5:It is my daughter’s ___________  birthday today.（九）

小题6:He likes __________ things with his friends. (share)

小题7:The clothes are the ______________. (robber)

小题8:Walk __________the street, you’ll find the post office.(cross)

小题9:How many __________ are there in Qianlong Grand Hotel? （wait）

小题10:My father laughs __________________ when he sees his friends.  (happy)

角化鳞状上皮中，由2～3层扁平细胞组成，细胞质内含嗜碱性透明角质颗粒，表面为正角化时，此层明显；表面为不全角化时，此层不明显。该层是

A．基底层

B．棘层

C．粒层

D．角化层

E．中间层

根据价层电子对互斥模型，判断下列分子或者离子的空间构型不是三角锥形的

A．PCl₃

B．H₃O^＋

C．HCHO

D．PH₃