It was not until the teacher had explained it three times _______ how to work out the problem.
The science of medicine, _____ progress has been very rapid lately, is perhaps the most important of all the science.
This is the largest clock in the world, _____ the minute hand is six meters long.
Sarah hopes to become a friend of _____ shares her interests.
Liu Xiang is ________ Yao Ming.
When and where to go for the on-salary holiday _____ yet.