单项选择题 Studies have shown that smoking is a factor for gastric cancer either by itself, or more ______ when in combination with another factor such as coal dust exposure or the consumption of alcohol.

单项选择题 It can cause a hip or wrist ______ from a simple fall, and it decreases life expectancy because it is the leading cause of accidental death in people aged forty-five to seventy-four.

单项选择题 Profitable for 35 ______ years, Secom has a 60% share of the domestic market and is also. expanding abroad.