英语中哪些副词有两种形式

两种形式的副词，我们语法学上称之为同源副词。
我举些例子，用简单英文注释的，请看：
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1) cheap: often used instead of cheaply, esp. in casual conversation and with
verbs like buy and sell
Do you like this shirt? I bought it really cheaply.
cheaply I can't sell you more cheaply.
2) clean: completely, used with (1) verb forget (2) the proposition over,
through (3) adv away out
I ~ forget. The ball sailed ~ over the roof.
The prisoner got ~ away. I am afraid I am clean out of food.
cleanly: precisely in a clean manner, often used with v cut.
He caught the ball ~ . The doctor cut ~ through the abdominal wall.
3) clear: not touching
Please stand clear of the gate.
clearly: distinctly, obviously, similar to the meaning of clear
I can't see ~ without my glasses.
We ~need to think again.
4) close: near
Come close, I want to tell you something.
closely: carefully, with great attention
Study this ~ it's very impor