【C16】A．becauseB．even ifC．sinceD．if

【C18】A．BecauseB．IfC．AlthoughD．Unless

【C16】A．BecauseB．WhenC．BeforeD．Although

【C5】A．becauseB．ifC．thoughD．when

【C3】A．BecauseB．AsC．SinceD．Although

【C6】A．unlessB．ifC．asD．since

【C9】A．becauseB．ifC．thoughD．when