What is 針? 快..............thx

注射（英語：Injection），俗稱打針，是一種利用注射器與針頭穿過皮膚，並將液體送入身體內的方法。是一種給藥途徑，注射所預期的作用位置，不一定是受注射的位置。
目前有多種不同的注射方法，包括真皮內注射（intradermal injection）、皮下注射（subcutaneous injection）、肌肉注射（intramuscular injection）、靜脈注射（intravenous injection），以及骨內輸液（Intraosseous Infusion）等。

An injection is an infusion method of putting liquid into the body, usually with a hollow needle and a syringe which is pierced through the skin to a sufficient depth for the material to be forced into the body. An injection follows a parenteral route of administration, that is, its effect is not necessarily local to the area in which the injection is administered; it is systemic.
There are several methods of injection or infusion, including intradermal, subcutaneous, intramuscular, intravenous, intraosseous, and intrapertitioneal . Long-acting forms of subcutaneous/ intramuscular injections are available for various drugs, and are called depot injections.

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