It is the presence or absence of this additional mechanism that differentiates the two theories observationally 這個額外機制的顯現(xiàn)與否,正是在觀測上區(qū)分此兩種學(xué)說的要件。
These additional mechanisms add powerful ways to add to or customize a type s functionality , but not without a significant cost 這些附加機制為添加或自定義類型的功能提供了功能強大的方式,但需要大量開銷。