单选题：He stood up, _____the large door and looked outside. There ..

— Why did he come back?— It is ______ he forgot to take his umbrella with him.A. for B. as C. since D. because

—Is Jack on duty today? —It_____ be him. It’s his turn tomorrow.A．mustn’tB．won’t C．can’tD．needn’t

When the rescue workers arrived, they were sad to see what _____ of the relics after the big fire. [ ]A. was remained B. remained C. was made D. made

To live in honor, _____he came from a poor family, was his ambition.A. thoughB. ifC. unless D. however

I am afraid I would have little influence over her ______ her mind was made up on any subject.A. until B. once C. though D. unless