There _____ be any difficulty about passing the road test since you have practiced a lot in the driving school. [ ]

A. mustn't

B. shan't

C. shouldn't

D. needn't

关于脑脊液正确的是（）

A.自外侧孔流入第三脑室

B.正中孔是脑脊液自脑室入蛛网膜下隙的惟一途径

C.为无色透明不含有机物的液体

D.由脑室脉络丛产生

E.以上均不是