题目内容：

It is believed that _____part lf the animals can't stay alive in water at 1,500 meters below _____sea level.
A ×;×
B a;a
C the;the
D ×;the

优质解答

A
that part ,part前已经有了"that",所以不用定冠词了.
(part后的if从句都是修饰part的)
sea level
海平线,特定的词组,不加冠词.