Match up the words which are similar in meaning: purpose, in the sphere of, to make, important, aim, proper, common, to work out, to vary, time, in the field of, significant, ray, to define, to operate, to develop, to differ, to show, method, to function, to demonstrate, technique, device, to determine, standard, to produce, suitable, beam, period, instrument.

Purpose - aim
to make -to produce
beam -  ray
time - period,
to work out, -  to operate,
 to define -  to determine
to show, - to demonstrate
important,  - significant
device, -  instrument.
proper - suitable,
common - standard,
 to vary - to differ, 
in the sphere of, - in the field of,
to develop, - to function
technique,  - method