The work is so difficult.I don't know____ A,how to doB.how t

The work is so difficult.I don't know____ A,how to doB.how t The math problem is so difficult,I don't know __ A how to do I really don't know____ A where to travel to B how to solve Children don't always know____.A.what to do it B.how to do i 1.This job is too difficult.I don't know____ The problem is very hard,I don't know how to work out._____ The morning sunrise is so beautiful that I don't know how to I don't know how to -------------the problem 单项选择 A work at The maths problem is so hard,I really don't know ____.A.how I don't know____ he is going to the party or not tonight;I'l I don’t know____ to visit the old man. So heavily____ that I didn't know how to go to the work.