get to grips with	begin to understand, cope with sth
make the grade	to deal with sth successfully
to be out of one's depth	unable to understand, control
have a good head for figures	be good at arythmetic
haven't a clue	have no knowledge of
slow on the uptake	sb who understands and learns things slowly
get on top of sth	reach a particular standard/succeed
talk the hind legs off a donkey	talk too much
the gift of a gab	talent to talk easily and persuasively
be head and shoulders above the rest	be more important, greater than the others
old boys	fromer students
be from the wrong side of the tracks	from the poor/less respectable part of town
smart alec	sb who thinks he's very clever
put one's foot in it	upset sb often by accident
of the old school	old-fashioned and conservative
put someone in his/her place	make sb understand they have done sth bad
be all at sea	confused
know sth inside out	know sth/sb very well
learn the ropes	become familiar with details of a profession
scratch the surface	examine a small part of the problem