I want to introduce my best friend to you.
A:fail to
B:would like to
C:can't
“观察DNA,RNA在细胞中分布”的实验中,下列正确的实验步骤是( )
如图所示,把卡片放在杯口上面,再把光滑的扣子放在卡片上。用手指使劲弹一下卡片,卡片飞了出去,则扣子( )