It is said that a reliable treatment for the disease will be applied at least two or three months away and still it ______on animals.

A．is testing

B．has tested

C．is being tested

D．has been tested

发明摩托车的是（）。

A、卡尔.本茨

B、保时捷

C、戴姆勒和迈巴赫

D、奥托