给下列问句选择合适的答语。
A. I'm 46 kilograms.
B. I'm 12 years old.
C. It's 5 tons.
D. Size 8．
E. I'm 1.64 metres.
① —What size are your shoes?
—____
② —How heavy are you?
③ —How tall are you?
④ —How old are you?
⑤ —How heavy is it?
若a→+b→=a→-b→=2a→，则向量a→+b→与a→的夹角为（ ）
严复被赞誉为“放眼世界，又葆有纯正中国心”。他的主要成就是（ ）
