Firstly, grammatically speaking a mood reflects how the speaker feels about an action. In Spanish and English languages, for instance, we have indicative –the most common–, imperative, subjunctive, etc. The latter expresses, in general, feelings of doubt, uncertainty, and subjectivity about actions, i.e., verbs that take the subjunctive are expressing desire, cause, doubt, volition, demand, request, necessity, and possibility. It is of interest, however, that the subjunctive is very common in Spanish, and as with any other verb tense, it is expressed on the inflection given to the specific verb. In addition, the subjunctive is used in dependent clauses depending on the tense of the verb in the main clause and the time relationship between the verb in the dependent clause and the subjunctive verb. Lastly, subjunctive in Spanish is used in four tenses, namely, present, present perfect, imperfect, and pluperfect. In English, on the other hand, subjunctive, per se, has little usage mainly because it is a very straight-forward, objective and fact-based language. Here are a couple of examples of subjunctive mood used in English:
a) I insist that you be quiet.
b) I recommend that you study for the exam.
However, the above examples are very limited and specific, and when one compares sentences such as “I doubt you are going to study [indicative]” to its equivalent in Spanish, we shall get this utterance “Dudo que vayas[subjunctive] a estudiar.” These sentences exemplify very well the difference of inflection, or lack of it, between one language and the other. Because the verb in this sentence is of doubt, the clause in Spanish has to be expressed in subjunctive; otherwise it would not render a proper utterance. Thus, the subjunctive mood is essential to Spanish.
Jan Hepworth (2003: 2) explains very well some of the verbs in Spanish in which their corresponding clauses have to be expressed using the subjunctive mood: querer (to want), esperar (to hope), temer (to fear), sentir (regret), preferir (to prefer), ordenar (to order), insistir (to insist), and prohibir (to prohibit). Let us remember also that the subjunctive is used in a clause starting with the relative pronoun “que” (which, that or who) as in “I hope that you come to the party” (Espero que vengas[subjunctive] a la fiesta). The conclusion that can be drawn from the above examples is that there are no distinctions between indicative and subjunctive mood in English, thus acquisition of the subjunctive in Spanish is very likely to create several issues for L2 learners.
Ellis, Rod. Second Language Acquisition. New York: OxfordUniversity Press, 2003.
Hepworth, Jan. “Subjunctive.” 2003. 27 October 2009 <www.esaudio.net/powerpoints/subjunctive.pdf>.