A:①②
B:②③
C:②④
D:③④
下列关于染色体的叙述中,错误的是( )
— It seems that Mr. Wu is standing there.— It ______ be him because he called me from Canada just now.
将一个直角三角板和一把直尺如图放置,如果∠α=43°,则∠β的度数是( ).