Question

Learning to write is learning to think. You don’t know things clearly _______ you can write them down.

A．unless

B．if

C．since

D．whether

Answer 1

A

unless 除非，如果不；if是否，如果；since由于，自从……以来；whether是否。句意：学习写作就是学习思考。如果你不能把它们写下来，你就不能了解事物。结合语境可知选A。