设f(x)及g(x)在[a,b]上连续,则下列命题 ①若在[a,b]上,f(x)≥
题型:单项选择题
问题:
设f(x)及g(x)在[a,b]上连续,则下列命题 ①若在[a,b]上,f(x)≥0,则f(x)≠0, ②若在[a,b]上,f(x)≥0,且,则在[a,b]上f(x)=0 ③若f(x)在[a,b]的任意子区间[α,β]上有,则f(x)=0() ④若在[a,b]上,f(x)≤g(x),且,则在[a,b]上f(x)≡g(x) 中正确的是
A.(A) ①、②.
B.(B) ①、②、③.
C.(C) ①、②、④.
D.(D) ①、②、③、④.