A:How
B:What
C:What a
D:How a
① a∥cb∥c} ⇒a∥b;② a∥γb∥γ} ⇒a∥b;③ α∥cβ∥c} ⇒α∥β;
④ α∥γβ∥γ} ⇒α∥β;⑤ α∥ca∥c} ⇒a∥α;⑥ a∥γα∥γ} ⇒a∥α.
其中正确的命题是____.(填序号)
— Yes, it made me _________ many times.