— Miss Wang,I feel very nervous with the competition approaching.

— ________.As long as you can finish it,it is a   victory.[ ]

A. Take your time  

B. Take it easy

C. No problem  

D. It's hard to say

混悬剂中结晶增长的主要原因是（）.

A.药物密度较大

B.粒度分布不均匀

C.δ电位降低

D.分散介质粘度过大