The construction able to takes an infinitive to show the subject’s ability to accomplish an action: We were able to finish the project thanks to a grant from a large corporation. The new submarine is able to dive twice as fast as the older model. Some people think able to should be avoided with passive constructions involving forms of the verb be: The problem was able to be solved by using a new method. Since the problem has no ability to accomplish an action, this reasoning goes, it is not able to do anything; therefore able to should not be used. In such cases, you can usually substitute can or could: The problem could be solved by using a new method. Keep in mind, however, that passive constructions using the verb get ascribe a more active role to their subjects, and here you can use able to: He was able to get himself accepted by a top law school.
