已知a+b=3,ab=1,则a2﹣ab+b2=( )
6
Although my parents are very busy, they still ______ a lot of time to us.
A.offer
B.devote
C.spend
D.provide
公共建筑防火门应选用()。
A.钢化玻璃
B.夹丝玻璃
C.夹层玻璃
D.镜面玻璃