皮肤的表皮细胞经常脱落而成为皮屑，但皮肤并不会因此而越来越薄，这是因为_______细胞有很强的分裂增生能力。

A．角质层

B．生发层

C．真皮层

D．皮下脂肪细胞

When Karen was young, she ____________ play in the kitchen. [ ]

A. can

B. can't

C. could

D. couldn't