"Measuring blood pressure and also heartbeat is/are important for everyone" "is" or "are" ? Why?
I think "is" is correct but I'm not sure.
Is the word "also" important here? Does it add another subject to the sentence?
Measuring is important.
On its own, "measuring" is clearly singular. The traditional label for this word is gerund -- a non-finite verb form that does the same kinds of jobs that a noun typically does. Here, it serves as the subject of the sentence, and the verb form that agrees with it is the word "is".
The clause "measuring are important" would be ungrammatical.
Measuring blood pressure is important.
Under a traditional analysis, a non-finite verb form does not create a predicate and take a subject. However, it still can take arguments and adjuncts. Here, "blood pressure" is the direct object of "measuring", and the gerund phrase "measuring blood pressure" is the complete subject of the sentence.
This complete gerund phrase is singular, just the same as the gerund on its own.
Measuring blood pressure and heart rate is important.
Here, there are two noun phrases in the direct object. The coordination "blood pressure and heart rate" is typically treated as a plural construction, but that doesn't make any difference to this sentence. A verb must agree with its subject, but there is no rule of agreement about the relationship between a verb and a direct object contained in its subject.
The clauses "measuring is important", "measuring it is important" and "measuring them is important" are all grammatically sound. In each, "is" agrees with "measuring". It doesn't matter whether the direct object exists, and it doesn't matter whether the direct object is singular or plural.