峰高一半处的峰宽称为半峰宽，其值等于（）
A.A
B.B
C.C
D.D
E.E
参考答案：E
This book is said to be a special one, which______ many events that cannot be found in other history books.
A．reads
B．writes
C．covers
D．prints
病原微生物进入机体能否引起疾病取决于（）
A.细菌的侵袭力
B.机体的抵抗力
C.细菌的毒力和机体的抵抗力
D.细菌的毒素
E.细菌的毒素与侵袭力
