Many sailors think that a thick fog is their ________ enemy.
You did me a huge favor. However, I lack words_________to express my thanks.
Tom was running out of time in the exam, but there still remained several questions_________.A. to be answered B. to answer C. answered D answering
If you need any more paper, I'll bring you_________.
An economist is____________expert who will know tomorrow why_________things he predicted yesterday didn't happen.
Having said goodbye to their friends, they ______________for home.