In Chomsky's theory "competence", which allows a native speaker to make sentences in his language, means______.

A．capacity of learning language

B．ability of speaking

C．knowledge of grammar rules

D．capacity of memorizing words

中低压玻璃钢管道安装后固定，为防止在浇注砂浆时引起管道的移动，可以采用绳索或带子把管道先固定在水泥座或其他固定支座上，两根固定带之间距离不应大于（）m。