这一方法是严谨的，需要精确。

The method is ___rigorous, requiring exactness.

实验室制定了严格的安全规程以确保所有实验都安全进行。

The lab has established ___rigorous safety protocols to ensure all experiments are conducted safely.

马拉松训练非常艰苦，需要极大的耐力。

Marathon training is extremely ___rigorous, requiring great endurance.