答案：D
A 30-year-old client with 7 months pregnancy reports severe leg cramps at night. Which nursing action would be most effective in helping her cope with these cramps
A. Suggesting that she walk for 1 hour twice per day.B. Advising her to take over-the-counter calcium supplements twice per day.C. Teaching her to dorsiflex her foot during the cramp.D. Instructing her to increase milk and cheese intake to 8 to 10 servings per day.
多自由度系统的固有频率和振型（模态）是如何求得的？
