My best friend,Kate,____ (promise)she won^t tell the secret to anyone else.

问题描述:

My best friend,Kate,____ (promise)she won^t tell the secret to anyone else.
要有理由奥!

promises就可以了(that 可以省掉,是个从句),因为后面用的是won't将来时;如果用promised 的话,后面应当是would not.