(1) ①在as/so long as之后，用一般现在时表示将来。

• I'll stay with you as long as there is a room free.
  只要有一个免费房间，我将与你住在一起。

②as/so long as常用来表示条件。

• You can take my car as long as you don't smash it up.
  只要你不把车弄坏，你可以开我的车。

③as long as可以表示时间。

• You can keep it as long as you like to.
  你可以想保管它多久就保管它多久。

 (2) on condition that意为“条件是……；只有在……条件下；只要”，that 常可省掉。

• You can go swimming on condition (that) you don't go too far from the riverbank.
  你可以去游泳，只要你别离河岸太远。
• Her parents allowed her to go on condition (that) she should get home before midnight.
  她父母允许她去，条件是她要在午夜前回到家里。

 (3) provided (that)意为“如果……的话；只要”，用作连接词，比较正式。

• They may swim provided (that) an adult accompanies them.
  只要有一个成年人陪同，他们就可以游泳。
• You may come with us provided that you arrive in time.
  只要你按时到，你可以跟我们来。

 (4) providing (that)的意思和用法与provided (that)相同。

• Providing (that) there is no opposition, we shall hold the meeting here.
  如果没有反对意见，我们将在这里开会。
• I promised to meet him there in a month, providing/provided I was sufficiently recovered to do so.
  我答应一个月后，在那里与他会面，如果我恢复得好可以这么做的话。