Give a wide berth to the breakwater means().
A. to keep clear of the breakwater
B. that there is much berth space near the breakwater
C. Don't drop anchor too close to the breakwater
D. to keep the breakwater within sight
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儿童掌握技能一般要经历感知、模仿、练习、创作这样几个过程。因此在手工活动中,一般采用感知――模仿――练习――创造的模式。
A. 正确
B. 错误
不适于定向应用的频率范围为()。
A. 30MHz~1GHz
B. 2GHz~40GHz
C. 1GHz~10GHz
D. 1GHz~100GHz