______ useful robot! It can help with the housework like a human servant.

6Although they are brothers, he’s not ______ as good-looking as his brother

You were brave enough to argue with Mr. Smith. —Well, now I regret _______ that.

I don’t think the experiment is _________ failure. Atleast we have gained _________experience for future success.

Without plenty of oral practice，you’ll find it hard to ______a conversation with native English speakers.