问题
选择题
It was not until then that I came to know that knowledge _______ only from practice.
A．had come
B．has come
C．came
D．comes
答案
D
主句虽然是过去时态，但从句所说明的是不受时间限制的真理或事实，名词性从句的谓语动词仍然用一般现在时。又如:He said Asia is the largest continent.