【C3】A．whileB．whichC．forD．where

【B13】A．whileB．whichC．wheneverD．when

A．whoB．whichC．where

下列属于分支结构的是（)。A、whileB、switchC、forD、以上都不是

【C3】A．whoseB．whichC．whereD．what

【C3】A．whatB．to whichC．in thatD．where

It was not until 1920 ______ regular broadcast began.A、whileB、whichC、thatD、since