He often helps his classmates their English. [ ]
A. to
B. with
C. on
D. in
答案：B
简述公路货物运输中装卸机械化方案的选择依据。
二进制数1001001.010的八进制数是（）
A.111.2
B.91.2
C.101.2
D.111.4
