What really worries us is ______ the explorers can accurately locate themselves with the device in case of bad weather.
It was hard for him to learn English in a family, in which ________ of the parents spoke the language.
—John,when shall we meet again,Thursday or Friday?—________.I'll be off to London then.(2012·重庆)
He had lost his temper and his health in the war and never found ________ of them again.(2010·重庆)
—How do you find your new classmates?—Most of them are kind, but ________ is so good to me as Bruce.
John has tried many ways to solve the physics problems, but ________ works.