If you __ a fire, please break the glass to sound the fire alarm.

Then moment _________ Mary will always remember is _________ Mr．Black gave her a lot of valuable advice on how to improve her writing．

He never reads anything ______ is not worth reading

Will you join us to play basketball on Saturdayafternoon—________, but I promised to go swimming with Eric.

Though ______ to see us，the president gave us a warmwelcome and showed us around