—— I can’t get through to the general manager’s office anyhow.
—— The line is busy. Someone _____ the telephone.
A. must use B. uses C. must have been using D. must be using
—— I can’t get through to the general manager’s office anyhow.
—— The line is busy. Someone _____ the telephone.
A. must use B. uses C. must have been using D. must be using
D