attach(to) (=to fix, fasten; join)
make an attempt at doing sth. (to do sth.)
attend to (=give one’s attention, care and thought)
attend on(upon)(=wait upon, serve, look after)
attitude to toward
attribute…to…(=to believe sth. to be the result of…)
on the average (=on average, on an average)
(be) aware of (=be conscious of , having knowledge or consciousness)
at the back of (=behind)
in the back of
on the back of
be on one’s back(=be ill in bed)
at one’s back(=supporting or favoring sb.)
have sb. at one ’s back
turn one’s back on sb. (=turn away from sb. in an impolite way)
behind one’s back
be based on upon
on the basis of
beat…at
begin with