Tìm khẳng định đúng trong các khẳng định sau.

A. $\underset{0}{\overset{1}{\int }}\sin \left(1-x\right)dx=\underset{0}{\overset{1}{\int }}sin\text{x}dx$   

B. $\underset{0}{\overset{1}{\int }}c\text{os}\left(1-x\right)dx=-\underset{0}{\overset{1}{\int }}\text{cosx}dx$

C. $\underset{0}{\overset{\frac{\pi }{2}}{\int }}c\text{os}\frac{x}{2}dx=\underset{0}{\overset{\frac{\pi }{2}}{\int }}c\text{osx}dx$ 

D. $\underset{0}{\overset{\frac{\pi }{2}}{\int }}\sin \frac{x}{2}dx=\underset{0}{\overset{\frac{\pi }{2}}{\int }}\sin dx$