－How about having a picnic with me?

 －I’d love to, ______ I’m afraid I have no time.

A. so    B. and     C. but

We didn't go home ______ the old man was sent to the hospital.

A. until          B. when        C. while

 John, work hard_______ you will make much progress.

A. or               B. nor                  C. but                  D. and

--What do you think of this skirt ?

--It’s beautiful and it fits me well ,_________ I like it very much .

A. since　　　　　　　 B. so　　　　　　　　　　　　 C. but

Bob is young, _______ he knows a lot.

A. because          B. so           C. but              D. unless

 The teacher speaks very loudly ____ all the students can hear her.

A. so that              B. because          C. since                D. when

 A tourist will easily lose his way in Beijing _________ he has a map or a guide.

     A. if     B. because     C. unless     D. when

— May I go to the concert with you?

— I’m afraid not ____ you have a ticket, because I have only one.

A. since　　 B. if　　 　 C. unless　　 　 D. though

To make our dreams come true，we aye supposed to set goals ______ then try our best to achieve them．

         A．or                     B．and                  C．but

 Jenny, put on your coat ________ you will catch a cold.

A. but              B. and              C. or               D. so