A:Have...met; has drive
B:Had...met; was drive
C:Did...meet; had been drive
D:Have...met; had drive
当a= 2 ,b=1时,代数式(a+2b)(a-2b)的值为( )
Parents should let their children make their own ____ (decide).
Shelly had prepared carefully for her biology examination so that she could be sure of passing it at her first ________.( )