express reservations about sth:对...存有疑惑,对...持保留意见
这里的reservation的意思是:保留意见;疑惑 a feeling of doubt about a plan or an idea
I have serious reservations about his ability to do the job.
我非常怀疑他有没有能力胜任这项工作。
They support the measures without reservation(= completely).
他们毫无保留地支持这些措施。
n. 预定,保留意见