1．(2011年龙岩检测)At 13，Samuel received a training course in drawing for three years，________he got a good opportunity for further development.
A．after that B．after which
C．after it D．after this
解析：选B。考查定语从句。after which he got a good opportunity for further development是非限制性定语从句。
2．(2011年东北三校模拟)There are 51 students in Class Three，________failed in the test.
A．all of which B．all of them
C．none of whom D．none of them
解析：选C。考查定语从句。后半句是非限制性定语从句，修饰先行词students，应用whom引导。因为前后两句之间没有并列连词，所以B、D两项不正确。
