As is known to all language learners, the newly learnt words will soon be forgotten unless ______ used in everyday communication.

 If a person has not had enough sleep, his actions will give him ___ during the day.

I’m afraid we can’t come, but thanks for the invitation_________.

Mr. Brook didn’t come back at the usual time last night. ______, he met some friends and stayed out until midnight.

To understand the grammar of the sentence, you must break it       into parts.