读图回答问题.
已知a、b是两条不重合的直线,α、β、γ是三个两两不重合的平面,给出下列四个命题:
①若a⊥α,a⊥β,则α∥β;
②若α⊥γ,β⊥γ,则α∥β;
③若α∥β,a⊂α,b⊂β,则a∥b;
④若α∥β,α∩γ=a,β∩γ=b,则a∥b.
其中正确命题的序号有____
Our Chinese teacher recommends new book to us every month and asks us to read by ourselves after school.
下列句子中,没有语病的一项是( )