26．(2015·江苏高考)It is so cold that you can't go outside ________ fully covered in thick clothes.
A．if B．unless
C．once D．when
解析：选B 考查状语从句。句意：天太冷，你不能去外面，除非你全裹在厚衣服里。unless相当于if ... not (如果……不)，符合句意。if“如果”；once“一旦”；when“当……的时候”，都不符合语意逻辑。________ fully covered in thick clothes为状语从句的省略，补充完整为“unless you are fully covered in thick clothes”。
33．(2015·湖南高考)________ the job takes a significant amount of time, most students agree that the experience is worth it.
A．If only B．After
C．Although D．In case
解析：选C 考查状语从句。句意：虽然这份工作要花大量的时间，但大多数学生都同意这次经历是值得的。句中的a significant amount of time与worth it之间构成对比，故用although引导让步状语从句。
20．（2015陕西高考）I believe you will have a wonderful time here ________ you get to know everyone else.
A．though B．as if
C．once D．so that
解析：选C 考查状语从句。句意：一旦你认识了这里的其他所有人，我相信你会在这里玩得很愉快的。根据句中的关键信息you will have a wonderful time和you get to know everyone else，可知应用once引导时间状语从句。
