adj. 非常坚硬的，强硬的，固执的 n. 坚硬无比之物
1977：“俄罗斯型流感”H1N1感染人类1977: "Russian flu" H1N1 Infects Humans
This heart is too weak to actually pump blood, which is the primary reason anyone would want an new heart. But the tissue has a lot of potential for patching heart muscles that have suffered damage.
The two extraordinary sex toys will go on display at an upcoming exhibition at the Asian Art Museum of San Francisco in the United States.
Wang Chunfa, executive secretary of the China Association for Science and Technology, has expressed deep concern over the retraction, which came just days after he met in Beijing with Arnout Jacobs, the head of Springer Nature for Greater China.