【C12】A．thenB．whileC．sinceD．where

在SQL的SELECT语句中，用于实现选择运算的是______。A．FORB．WHILEC．IFD．WHERE

【C12】A．whenB．whateverC．whereD．how

【C12】A．sinceB．in whereC．whereD．which

【C12】A．becauseB．whileC．althoughD．so

______I was talking to Barbara, I learned that Tony was in hospital.A．UnlessB．WhileC．Since

A. once B. whileC. since D. unless