引种的方法和程序是什么?
参考答案:引种目标的确定,引种材料的收集,引种材料的检疫,引种材料的驯化选择,引种试验,包括观察试验,品种比较试验和区域试验,栽培试验。
根据短文内容,用括号内所给动词的适当形式填空,必要时可加助动词或情态动词。
Li Wei is a middle school student. He 小题1: (live) in Linshu town. Every day he 小题2: (go) to school by bike. He 小题3: (not be) to a foreign country before. Next week he 小题4: (go) to Singapore with his parents. They plan 小题5: (stay) in Singapore for a week.
“Traveling to Singapore is a dream for me for a few months,” Li Wei said to his friend Jim. “ It 小题6: (come) true soon.” He wants to visit the “Night Safari”. He also 小题7: (want) to try Chinese food in Singapore.
在分线盘上测量()线端子间的交流电压,就能判断道岔表示电压是否送出室外。
A、X1(或X2)与X3
B、X1(或X2)与X4
C、X1与X2
D、X3与X4