下列各式中,计算结果为81﹣x2的是[ ]
A.(x+9)(x﹣9)
B.(x+9)(﹣x﹣9)
C.(﹣x+9)(﹣x﹣9)
D.(﹣x﹣9)(x﹣9)
答案:D
美国的教师职业就业,首先需要持有有效的(),还需要参加()方能成为正式教师。
— Do you think many people will_____ at Bob's party?
— Of course, he is a generous man. [ ]
A. make up
B. pick up
C. turn up
D. give up