Questions with active vs. passive voice

There is a simple way of determining whether active or passive voice is needed. In an active voice sentence, the subject is the person or thing that does the action. In a passive voice sentence, the subject of the sentence is affected by the action of the doer.
Active form = S + V + (O)    The police arrested my uncle.
Passive form = S + be + v.3    My uncle was arrested (by the police).
To answer the question on active and passive voice correctly, you need to identify whether the subject does the action or receives the action.

Let’s look at the first example:
1. More information can __________ from our website.
    a) obtain
    b) be obtained
    c) obtainable
    d) be obtaining
The subject of the above sentence is “information” which cannot do any action, so it cannot obtain anything. “Information” can be obtained by people (receiving the action), so the verb must be in passive form. The correct answer is b) be obtained.

Look at the second example:
2. A car went out of control and _______ into the back of a truck.
    a) crashed
    b) was crashed
    c) crashing
    d) were crashing
Here, the subject is “A car” which crashed or hit another thing. In other words, “A car” is the doer of the action (crashing), so it should be in active form. There are 2 active verbs in the choices: a) crashed and d) were crashing. The subject is singular, so “were crashing” does not fit. Therefore, the answer is a) crashed.