B.xiaqu下去, indicating continuation of an action in the future.

 

2.1     Ràng shuōxiàqu.  

让他说下去。

Let him go on (talking).

 

2.2     Yàoshì zhèyàng liànxiàqu, huì xué de hěn hǎo. 

要是这样练下去,你会学得很好。

If you keep practicing like this, you will study well.