问题补充:
They were walking a forest after they swam the river .
A. through, cross
B. across ,through
C. through, across
D. across, across
答案:
A. through, cross
B. across ,through
(答案→)C. through, across
D. across, across
解析:through通过,强调从内部通过;cross交叉的,相反的,不能用作介词;across穿过,横穿。句意:在他们游过这条河后,他们正在穿过一座森林。前文从森林内部通过,下文从河面穿过,故选C。