【C6】A．unlessB．ifC．asD．since

【C3】A．likeB．as ifC．asD．seems like

【C13】A．althoughB．ifC．whenD．since

【C15】A．UnlessB．IfC．BecauseD．Since

【C6】A．UnlessB．IfC．ThoughD．As

【C2】A．sinceB．ifC．asD．while

【C10】A．UnlessB．AlthoughC．SinceD．If