So you missed the lecture given by ProfessorSmith—- ____I got there 30 minutes before it finished

With so many things mixed up it’s hard to _______ what’s that.

What I’m interested in is radios and telephones, so I’d like to study __________ Engineering during my four years in university.

Those tigers in the forest never_____ people unless they are very hungry.

It is reported that nowadays more and more children _____ playing computer games.