下列实验过程中，始终无明显现象的是（　　）

A．HCl通入Fe（NO₃）₂溶液中

B．SO₂通入溴水中

C．NH₃通入CuSO₄溶液中

D．CO₂通入Ba（NO₃）₂溶液中

In spite of relatively costly, the diesel engine is highly efficient and needs servicing infrequently.

A．Despite

B．It is

C．There is

D．Even though