We should consider the students' request _____ the school library provide more books on popular science. [ ]

A. that

B. when

C. which

D. where

杠杆加载试验中，杠杆制作方便，荷载值稳定不变，当结构有变形时，荷载可以保持恒定，对于下列何种试验尤为适用（）？

A.动力荷载

B.循环荷载

C.持久荷载

D.较大的短期荷载