Which word completes each set of collocations or fixed phrases?
a) an instrument _panel_______
a panel of experts
a control panel
a wooden panel

b) a [secret] ballot
a [secret] agent
keep it a [secret]
meet in [secret]
the [secret] of success

c) take [stock] of the situation
it's out of [stock]
the [stock] exchange
the [stock] market

d) a [time] sheet
a [time] zone
only [time] will tell
long [time] no see
for the [time] being

e) a [child] minder
[child] abuse
[child] care facilities
a [child] prodigy
behaving like a [child]