Year after year a dedicated Swedish chemist worked to find a substance which, when【C1】____

__nitroglycerine (硝化甘油), would make explosives safer to handle【C2】______weakening their force. He had a personal【C3】______scientific reason to pursue his search, because his【C4】______brother had been killed when a can of nitroglycerine【C5】______exploded. The oily liquid had been 【C6】______for so many disasters that its【C7】______ had finally been outlawed by many countries.

While【C8】______a new formula one morning, the doctor broke a test tube and gashed (划开) his finger. He was daubing (涂搽) the【C9】______with collodion (火棉胶), a coating solution of gun-cotton dissolved in ether-alcohol (乙醚),【C10】______the idea struck him —mix collodion with the nitroglycerine!【C11】______was the answer. The new mixture,【C12】______blasting gelatine (爆胶), was not only【C13】______safe to handle as dynamite, but it was also one-and-a-half times more powerful! In fact, so powerful 【C14】______ that it paved the way for a whole new【C15】______in construction and engineering. Mines were【C16】______, roads were built, and canals were cut at a speed once【C17】______impossible. It had another use, also —death and destruction in warfare. Its inventor had believed that the power of his new【C18】______ would so awe the military mind that it would actually be a deterrent (威慑物) to war.【C19】______it became a weapon that brought death to millions of soldiers and【C20】______.

【C1】

A．mixing with

B．mixed with

C．was mixing with

D．was mixed with