You can’t really prepare for the questions the interviewer will ask—you’ll just have to play it by ear,I’m afraid.

你没法准备面试官要问的问题，恐怕只能随机应变了。

In dealing with that unpredictable man, you simply cannot follow a prearranged plan, you have to play it by ear.

和个捉摸不定的人打交道, 你简直无法按预定计划行事, 只好随机应变。