My father warned me going to the West Coast because it was crowded with tourists.A. byB.

问题补充：

My father warned me going to the West Coast because it was crowded with tourists.

A. by

B. on

C. for

D. against

答案：

A. by

B. on

C. for

(答案→)D. against

解析：考查固定词组，warn against意思“警告…不要”，句子意思“我的爸爸警告我不要去新加坡因为那里满是游客”，固定词组be crowed with意思“满是”