With the word “ PM2.5” ________ appearing in media reports, people pay greater attention to it and seek health tips for smoggy days.
70. I know it is difficult __________ him to talk like the lecturer, but I think he should grasp every chance .
69. With the guide leading the way, the visitors were able to travel through the forest not by air but _____ foot.
68. When the boy playing by the river fell into the river, I was out of the room _______.
67. The Prime Minister was more fit __________ his office than anyone else.
66. When the good news that our football team won the championship, the hall was at once _______ great joy.