Together with, as well as and along with

These phrases show addition, but they are not the same as and. When we connect two singular subjects with and, the verb has to be plural in number.

John and Alice are colleagues. (NOT John and Alice is colleagues.)

We can use phrases such as as well as and along with to connect two subjects. In this case, the verb usually agrees with the first subject. So for example, if the first subject is singular, the verb is also likely to be singular. If the first subject is plural, then the verb is likely to be plural.

Compare:

The screenplay, as well as the cinematography, was superb. (NOT The screenplay, as well as the cinematography, were superb.)
The screenplay and the cinematography are superb.
The manager, as well as his colleagues, is responsible for this.
The manager and his colleagues are responsible for this.
The students, as well as the teacher, have gone missing.

Either and neither

The pronouns either and neither might seem to be referring to two things but they are singular and require singular verbs. Note that we put a plural noun after either of and neither of.

Neither of the two fans is working. (NOT Neither of the two fans are working.)
‘Which one do you do want?’ ‘Either isfine with me.’

Or

The conjunction or is also different. It doesn’t conjoin as and does. When or or nor is used to connect two subjects, the subject closer to the verb determines the number of the verb. So if the second subject is plural, the verb is also likely to be plural.

Either the manager or his representatives are going to attend the meeting. (Here the plural verb are agrees with the plural subject representatives.)

Neither the directors nor their representative was contactable. (Here the singular verb was agrees with the singular subject representative.)