These epithelial elements arise embryologically from foregut endoderm in the process of bronchial tubular growth.这些表皮细胞在胚胎学上把源于支气管生长过程中的前内脏叫内胚层.Successive section sees endoderm has exfoliate phenomenon.连续切片见内皮层有剥脱现象....
他坐在书桌后吃力地写着，用的是一支部队发的钢笔。He sat behind a desk laboriously writing with an Army issue pen.我匆忙装好食品篮，吃力地把它拎上车子。I hastily packed the hamper and lugged it to the car.他吃力地站了起来。He hauled himself to his feet....
She heard the priest's familiar, flat footfall on the staircase.她听到楼梯上传来牧师那熟悉的单调脚步声。They walked down the staircase together.他们一起下了楼梯。He followed her up a rickety staircase to a squalid bedsit...他跟着她上了一段摇摇晃晃的楼梯，来到了一间...