（1）∠t=100 那剩下两个肯定是等腰的脚，所以r为40 充分
（2）∠s=40 那剩下两角可能是等腰的脚 70 70 也可能不是，所以R可以等于40 也可以等于70 不确定 不充分
- 【OG18-P680-668题】In a review of 2,000 studies of human behavior that date back to the 1940s, two Swiss psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size, none could be taken seriously.
- 【OG18-P680-671题】Manufacturers rate batteries in watt-hours; if they rate the watt-hour higher, the longer the battery can be expected to last.
- The passage provides information to support which of the following statement about La Nina?
- The author of the passage would most likely agree with which of the following statements about the link between increased solar activity and certain seasonal weather changes on the Earth?
- Following several years of declining advertising sales, the Greenville Times reorganized its advertising sales force two years ago. Before the reorganization, the sales force was organized geographically, with some sales representatives concentrating on city-center businesses and others concentrating on different outlying regions. The reorganization attempted to increase the sales representatives’ knowledge of clients’ businesses by having each sales representative deal with only one type of industry or of retailing. After the reorganization, advertising sales increased.In assessing whether the improvement in advertising sales can properly be attributed to the reorganization, it would be helpful to find out each of the following EXCEPT: