They came to the conclusion ________ by a computer.

A．that not all things can be done

B．because of not all things be done

C．being not all things can be done

D．because not all things can be done

在高速行驶时，不应换向。若要换向，应先踏下制动踏板充分减速后（一般小于20km/h），再进行换向。