Yang Liwei’s journey into ____ space took him 600,000 kilometres in ____ orbit, around the earth 14 times, in just over 21 hours.
---Is he here now?---No, I ___ he ___ here by now.
My brother tried ___, but still he couldn't work out this maths problem.
He seemed as if he ___ his homework when his mother came in.
The poster says that a writer and poet ___ to give us a talk on English next week.
How this kind of plant can be ____ in a special way is still unknown to us.