【C13】A．whenB．ifC．beforeD．since

【C13】A．thoughB．as ifC．ifD．as

【C13】A．whenB．whatC．thatD．if

【C13】A．WhenB．SinceC．AlthoughD．Unless

【C13】A．althoughB．ifC．whenD．since

【C9】A．whenB．ifC．untilD．after

【C6】A．unlessB．ifC．asD．since