Ifyouhaveanyproblemsduringyourstudyhere,pleasedonot_______tocallmeforhelp

This river forms a natural _______ between China and Korea.

We can not trust him any more because he often________ his duty.

Whenmakingmoderncameras,peoplebeganto_______plasticsformetal.

IntheUnitedStates,theforeignpolicyisdecidedbythe________government,notbyeachstate.