It is usually warm in my hometown in March, but it _____ be rather cold sometimes.[ ]

A. must

B. need

C. can

D. would

锅炉进行水压试验的时侯，当压力升高到工作压力后，应立即停止升压，在此压力下保持（）min，若压力变化不超过0.2MPa，即可继续做超压水压试验。