It was not until 1938 the first colour TV programme was broadcast.
A. which
B. that
C. when
D. on which
网友回答
A. which
(答案→)B. that
C. when
D. on which
解析：
试题分析:考查强调句型。从句意可知即使不填选项，句子意思仍然完整，所以判断为强调句型。强调句型的特点是去掉it is ….that 部分，句意完整通顺，所以答案为B。句意：直到1938年第一个彩色电视节目才被播出。