——Be quiet! Mr Smith is coming.——Don't worry. It__________be him. Mr Smith is much taller.
A:mustn't
B:must
C:can't
D:needn't
一张长方形的红纸,长1.2米,宽0.8米.用它做成两条直角边都是0.2米的直角三角形小旗,最多可以做____
把一个长方形剪成两部分,它的周长与原来比( )