在先的

Mary scraped the residue of food from the plates before putting them under water.

玛丽在把盘子放入水之前刮去上面食物残渣。

You should gather yourself together firstly under conditions of great danger.

在极其危险情况下你应当控制住自己。

There's a special enclosure where you can look at the horses before the race starts.

"这里有一处特备围场,在比赛前你看看马。"

It seems wise to reconnoiter before entering the town.

在进入那城前, 侦察一下是明智。

Filter out all the dirt before using the water.

在用水前将其中不清洁东西过滤掉。

Xanthone was efficiently synthesized from o-chlorobenzoic acid first by etherization and then by Friedel-Crafts reaction in the presence of aluminium trichloride.

邻氯苯甲酸为原料,进行醚化,再在三氯化铝作用下进行-应,简洁、高效合成呫吨酮。

The mechanic explained that they would have to make good the damage to the body of the car before they resprayed it.

修理工解释说，在给车重新喷漆之前，他们得把车身毁坏地方修理好。

The orbiting Discovery crew on the way Sunday to rewire the International Space Station first had to make sure the shuttle's heat shield(heatshield) wasn't damaged during lift-off.

星期日，负责发现号轨道工作人员在跟国际空间站接轨前，必须确定热障在起飞时没有损坏。