29. Can you say _____ certain when he will come here?
He felt so proud as the audience were shouting loudly __________ his performance.
The river forms the __________ between the heavy industrial and light industrial areas of the city.
Measures have been taken __________ the spread of the HIV.
In __________ preparation for Shenzhou If, scientists need __________ knowledge of weather changes.
—Thanks so much for everything. You have certainly made my stay very pleasant.—__________.