英语4选1（should,had better,must,have）You _______ to tell me the truth if you want my help.A.should B.had better C.must D.have我选了B

HAVE TO DO STH = SHOULD DO STH = HAD BETTER DO STH = MUST DO STH
意思上差不多，但只有HAVE 可以跟TO

有to 的话，当然要选have
若没有to 四个都行，主要再考虑语境

have to do sth.
had better do sth.
should do sth.
must do sth.

you had better + do sth, have to 是不的不，必须之意，根据题意就该选D

should ,must都是情态动词后面要加原形
had better + do
而have to是固定搭配表示不得不
意思上,你不得不告诉我真相如果你需要帮助.意思通顺,故选D

B 表示“识相的就告诉我实情”，语气太刚烈；
D 表示“必须，有义务这样做”，是得到我帮助的前提。

have to 不得不