下列词不能替换“第以人心积习既久”中“第”的是（）
A.皆
B.但
C.惟
D.直
E.特
参考答案：A
One and a half hours ____ all I can spare now. [ ]
A. is
B. are
C. was
D. were
血小板数为多少时，不进行手术即可发生自发性出血()
A．≤50×10/L
B．≤30×10/L
C．≤20×10/L
D．≤10×10/L
E．≤100×10/L
