_______ a certain doubt among the people as to the practical

_______ a certain doubt among the people as to the practical ________a certain doubt among the people as to the practical _______a certain doubt among the people as to the practical _____ a certain doubt among the people as to the practical v _____a certain doubt among the people as to the practical pr _______ a certain doubt among to the students as to the nece -------a certain doubt among the students as to the necessit There remains a certain doubt among the people as to the pra _There remains_ a certain doubt among the people as to the p ---There existed----a certain doubt among the students as to 高中英语语法题~._____ a certain doubt among the young people as to 英语从句题1._____a certain doubt among the people as to the pract