问题
选择题
(2013·成都一模)________ all the homework assigned by the school, the students have to work at it till midnight.
A．Completing
B．To complete
C．Having completed
D．To have completed
答案
答案：B
选B 考查非谓语动词。此处为目的状语， 因此使用不定式，排除A和C，而且不强调完成，因此使用不定式的一般式，故选B。