刃磨标准麻花名时,若顶角不等于118°时,两切削刃则为()。
A.直线
B.凹或凸
C.凹
D.凸
参考答案:B
B.调谐是电磁波发射的过程,调制是电磁波接收的过程
C.在双缝干涉实验中,若仅将入射光由绿光改为红光,则相邻干涉条纹间距变窄
D.考虑相对论效应,一沿自身长度方向高速运动的杆长总比静止时的杆长短
Despite (1) that alcoholic beverages may (2) , a leading medical expert is advising: don’t (3) just yet. Anybody who’s ever worked in a hospital sees the hospital is full of patients that have (4) disease, but the hospital is not full of patients that have disease related to cholesterol and (5) . In an (6) in the current New England Journal of Medicine, Dr. Goldberg of Columbia University said it is time to see (7) prevents heart disease. Such a study would give (8) to one group of heart disease patients and not to another, and see (9) . In the latest study, which followed (10) over a 12-year period, researchers found that those who drank (11) drinks per week (12) of heart attack by (13) compared to (14) . The lead author, (15) Kenneth Mukamal of Beth Israel Deaconess Medical Center in Boston, insists his study is (16) . For one thing, other studies have not looked at (17) . Dr. Mukamal says (18) also appear to settle which alcoholic beverage are (19) . "Beer and spirits, beer and liquor, were most ply (20) ."