Question

你不能指望一周内就能学好一门外语（翻译成英语）

Answer 1

You can't expect to master a foreign language in one week.

Answer 2

You can't expect to make good a foreign language in a week.
或则
You woundt expect to master a foreign language in one week.

Answer 3

You cannot count on master a foreign language within one week.

Answer 4

you cannot expect yourself to apprend a foreign language in a week.