几道英语题阿！SOS

1.They do not want let their friends () A.up B.down C.on 2.If he ()harder, he will A.study B.will study C.STUDIES

B C

B let sb down

1. B let sb down 使...失望

2. C if引导的条件状语从句，用一般现在时表示将来

1.b

let sb down..让某人失望

2.c

if条件状语从句

B,let....down..使...失望

C，条件状语从句，一般时代替将来时