单项选择题
As I regard it, you can widen the ______ of these improvements through your active participation.
单项选择题 The introduction of fabrics made from rayon, nylon and other ______ fibers has made many changes in our civilization.
单项选择题 After 10 hours at the wheel of the car, he began to feel the ______.
单项选择题 "If we fail to act now, "said Tom, "We'll find ourselves ______ in action later on."
