都可以!1.Im confident of success/I have confidence in gaining successs.2.I'm pretty confident that you can do this thing well.3.I'm worried about his capability of completing the task.4.Leave it to him, I'm not worried at all/ I'm quite worried.5.I suggest that you stay at home these days, try not to go anywhere.Especially places crowded with people.希望对你有帮助! :D