1.I have no doubt in my mind _____ they will be glad to see me.

1.I have no doubt in my mind _____ they will be glad to see me.
A.that B.how C.why D.whether
2.After leaving school,he sold newspapers and delivered mail.(同意)
After ______ _______ school,he sold newspapers and delivered mail.
3.Jack studies English hard.Jim doesn't study English hard.(合并一句)
Jim ______ study English so hard _______ Jack.