选择合适的词组, 并用其正确的形式填在横线上。
run across the road put out be born go on a picnic leave for
be made of have to take one’s advice more than plenty of
将枝条的一部分用土埋起来，促使其生根抽条，然后与母体分开，成为新植株，这种方法叫____。
