―I think it’s too late to say sorry to Kate.

―Never mind. _______.

A．Good medicine tastes bitter

B．Better late than never

C．All good things come to an end

D．A man becomes learned by asking questions

可纠正脑细胞缺陷的是（）

A.谷氨酸

B.胱氨酸

C.甘氨酸

D.酪氨酸

E.色氨酸