Expresses an action that is ongoing or a state that is continuing in the present (can also be used to talk about an action in the past with an emphasis on the result or state).250人が 列車に 乗っていました。
Noun + は + information + ですN5
Sentence pattern to introduce a topic, emphasize information about that topic.列車は 2023年に 始まりました。
Noun + の + NounN5
Noun-modifying sentence pattern, expressing the possessive relationship or description between two nouns.メキシコの 列車が 脱線しました。