警察正在努力查明他是如何死亡的。

The police are trying to ___establish how he died.

总之，很难确定人们如何选择购买他们所买的东西。

In summary, it is difficult to ___establish how people choose to buy what they buy.

科学家旨在通过广泛研究确定这种疾病的原因。

Scientists aim to ___establish the cause of the disease through extensive research.