Several months later, he found his deskmate very difficult _______.

A．to get along with

B．getting along with

C．to get along

D．to be gotten along with

下列说法中正确的是

A．酸性氧化物都是非金属氧化物

B．所有物质中都存在化学键

C．含有极性键的分子一定是极性分子

D．含有离子键的化合物一定是离子化合物