No one responded when Tom was speaking, so he paused _______ before continuing to draw our attention.

It’s always difficult being in a foreign country, ___________if you can’t speak the language.

--- In what way will you use your portable computer?--- I’ll use it _____ for giving lectures at home and abroad. 

These natural parks are very important for preserving many animals, which would ______ run the risk of becoming extinct(灭绝的)．

Work gets done ________ when people do it together, and the rewards are higher too.