Ⅰ.单词拼写
1.Zhang Wenhong said that he was   (乐观的)about Chinese COVID-19 vaccines. 
2.It's   (不确定的)whether they will accept the plan. 
3.The wind blew in from the   (沙漠)and covered everything with sand. 
4.To keep safe, drivers and passengers should fasten the safety b   .