【C18】A．thoughB．whileC．beforeD．until

【C18】A．afterB．atC．beforeD．during

【C18】A．becauseB．whileC．whenD．if

【C8】A．thoughB．whileC．so thatD．as

【C18】A．thoughB．except thatC．becauseD．unless

【C6】A．sinceB．whileC．whereasD．before

【C5】A．SinceB．After a whileC．AgainD．Before long