The contract specification for BankAccount includes a class-wide invariant that the balance must always be greater than or equal to zero (sorry, no overdrafts allowed!).
A recent wide-ranging society of public opinion found 90 percent of people still placing themselves in particular class; 73 percent agreed that class was still a vital part of British society; and 52 percent thought there were still sharp class differences.
He and other biologists studying a wide variety of organisms have found that these particular RNA's direct, in large part, the synthesis of histones, a class of proteins that bind to DNA.
他和其他研究多种生物的生物学家发现，这些特殊的 RNA 在很大程度上直接影响组蛋白的合成，组蛋白是一类与 DNA 结合的蛋白质。