单项选择题
It is said that a collection of paintings by David is ______ exhibition at the Museum.
单项选择题 Students in our school often go ______ field trips.
单项选择题 During her study in Massachusetts Institute of Technology she has got the degree ______ PhD, and it is a degree ______ chemistry.
单项选择题 I've got tired ______ walking and want to have a rest.
