Many sentences in Japanese are formed with a verb alone, especially in spoken Japanese. Since the verb form doesn't change depending on the number of the subject or the gender of the subject, it does not need to be marked, as this information is perfectly clear from the context.
Another grammatical difference between the languages that often leads to confusion when people from the two language cultures are speaking with each other, but not within each language community, is the use of yes and no. Within the languages of the world, it turns out that there are two major systems for using these words--Japanese belongs in one group and English in the other. It takes training to make the switch between them. Questions in Japanese are formed either by using a rising intonation at the end of a sentence or by adding a particle ka, to the end of the sentence.
Densha ga kimasu. The train is coming.
Densha ga kimasu?(rising intonation) The train is coming?
Densha ga kimasu ka? Is the train coming?
As these examples remind us, English can make sentences by changing the intonation at the end too, in speech, or by changing the word order of the subject and part of the predicate. For all these questions, the answers have the same meaning in Japanese and English. In Japanese, hai if the train is coming, and iie if it's not; for English, "yes" if the train is coming and "no" if it's not.
But if the question is asked using a negative, as in the following examples, then the answers in the two languages are not the same.
Densha ga kimasen. The train is not coming. (masen instead of masu makes it negative)
Densha ga kimasen? The train is not coming?
Densha ga kimasen ka? Isn't the train coming?
In the questions above, if the train is coming, the answer is iie, and if the train is not coming, the answer is hai. The Japanese answer is more like saying, "Yes, your assumption is correct; the train is not coming" or "No, your assumption is incorrect; the train is not not coming." So it is the assumption part that the listener is responding to by means of hai and iie. In English, however, the answer depends on the train itself, not on the assumption of the speaker: "Yes, the train is coming" or "No, the train is not coming." The actual wording of the question, that is, whether the question is asked negatively or affirmatively, is irrelevant.
Another difference between the two languages is observed in the way the two groups of people signal social factors through grammatical elements, especially verbs. Japanese people using Japanese in different social situations are taught to be careful about verb forms that are appropriate to the social goals of the interaction. For example, American English speakers decide, on social grounds how to compose a question: "Would you like a cup of coffee, Dad?," "D'you want some coffee?," "Don't you want some coffee?," "How about some coffee?," "Coffee?" or "Here, have some coffee," "There's coffee here for anyone who wants it," etc. Japanese speakers make similar choices.