A:would
B:could
C:had to
D:ought to
Take ____! Don't ____ off the tree.
在进行“调查人群中的遗传病”活动时,最好选择的疾病是( )
填空:
①+3.3的相反数是____;
②-5的相反数是____;
③____的相反数是-5.6;
④-(-8)是____的相反数;
⑤-(+6)是____的相反数.