5.
给出下列命题:
\(①\)\(\left. \int \right.\rlap{_{b}}{^{a}}\)
\(1dx=\)\(\left. \int \right.\rlap{_{a}}{^{b}}\)
\(1dt=b-a(a,b\)为常数且\(a < b)\); \(②\)\(\left. \int \right.\rlap{^{0}}{_{-1}}\)
\(x\)\({\,\!}^{2}\)
\(dx=\)\(\left. \int \right.\rlap{_{0}}{^{1}}\)
\(x\)\({\,\!}^{2}\)
\(dx\); \(③\)曲线\(y=\sin x\),\(x∈[0,2π]\)与直线\(y=0\)围成的两个封闭区域的面积之和为\(2\). 其中正确命题的个数为\((\) \()\)