Question

We were going out for a walk ________ it began to rai

We were going out for a walk ________ it began to rain. A．while B．before C．as D．when

Answer 1

D
试题分析：考查固定句型。固定句型：Be
doing
sth
when…正要做某事，在这时（发生意料之外的事情）。When在…那时（并列连词）。句意;我们正要出去散步，在这时开始下雨了。故D正确。
点评：when作为并列连词，意为：在那时；常与be
about
to
do
sth;
be
doing
sth
连用。When后面接意料之外的事情。