小明第一次跳绳跳了87个,第二次跳了80个,第一次比第二次多跳几个?
87-80=7(个)
病原体由传染源体内排出后,侵入另一易感机体,其在外界环境中所经历的途径称为()
A.传播范围
B.传播途径
C.传播机制
D.传播地域
E.传播链
I had to report the accident _______ length as the reporter asked me to describe it _______ detail.
A.in, in
B.at, in
C.at, at
D.in, at