It has been known for a long time that there is a first relationship between the heart and the liver.
举一反三
- That rich man has been dead for a long time but his ______ is still not known to the public.
- I have known her for a long time. / She........................ to me for a long time. A: has known B: has been known C: is known
- The relationship between employers and employees has been studied ________.
- It has been a long time since I ______ her in Australia.
- Olivia has been living at the _________ of my heart ever since we first met.