1. The current from these generators will add up to make a total flow of 500 amperes. (这些并联的发电机所产生的电流累计在一起, 总电流达到 500 安培。)
2. However, each country still retains its own policy. (但是,每个国家仍然保留自己的关税政策。)
3.The little boy laughed when his sister his ribs. (当姐姐搔小男孩的肋骨时,他笑了。)
4. The country is by severe economic problems. (该国为严重的经济问题所困。)
答案:1. parallel 2. tariff 3. tickled 4. beset