Explanation: The subjunctive mood is the verb form used to express a wish, a suggestion, a command, or a condition that is contrary to fact. From the given options, the revision that changes the underlined verb (was) to the subjunctive mood, is the corresponding to option A: change was to were, because the subjunctive form of the verb "to be" is "were." The complete answer would be: If the test were easier, teachers would not know what students really learned.
Sailors often used shorelines and islands to help them know their location because they have no map from which they got guidance. For example, an old sailor does not use map for traveling in the ocean due to its experience and some identification or symbols which he remembered that give him information about the way. These identification or symbols must be shorelines and islands because there is no other thing present in the ocean except these so the sailors used these symbols to know their location.
I'm sure there were some differences but no matter what slaves were treated like property and work forces. They were used to complete a task in both the US and South America, they were treated poorly as well.