①若m⊥α,m∥β,则α⊥β;

②若直线m,n与α所成的角相等,则m∥n;

③若α∩β=l,mα,nβ,m、n是异面直线,则m与n至多有一条与l平行;

④若α∩β=l,β∩γ=m,γ∩α=n,l∥γ,则m∥n.

其中真命题的序号是______________.(写出所有真命题的序号)

A.p₁＞p₂                                       B.p₁=p₂

C.p₁＜p₂                                       D.p₁与p₂的大小不确定

A.［0,+∞)                                    B.［3-,3+］

C.［0,］                                   D.［0,1+］

A.2                 B.              C.2+              D.

A.有3个                                    B.有2个

C.有1个                                    D.有0个

A.60种               B.70种                C.80种               D.120种

A.n(n-1)            B.n(n+1)             C.n-1                 D.n

A.［,］                              B.［,］

C.［,］                              D.［,］