题干
I'm weak in English. Li Yan often _______ me _______ my English.
A：help, with
B：helps, with
C：helping, in
D：to help, in
答案(点此获取答案解析）
B
I'm weak in English. Li Yan often _______ me _______ my English.
A：help, with
B：helps, with
C：helping, in
D：to help, in
，则向量a与b的夹角为 （ ）
