湯姆在自言自語。

Tom is talking to himself.

Tom's talking to himself.

Source: Tatoeba

Sentence Composition

1 湯姆 Tāngmǔ Tom (name)
2 在 zài
  1. to exist; to be alive
  2. (of sb or sth) to be (located) at
  3. (used before a verb to indicate an action in progress)
3 自言自語 zìyánzìyǔ (idiom) to talk to oneself; to think aloud; to soliloquize