You can split the sentences into words, keep only words that are part of your dictionary and paste them in one sentence again.
DF1$Text1 <- sapply(strsplit(DF1$Text, '\s+'), function(x)
paste0(Filter(english.words, x), collapse = ' '))
Here I have created a new column called Text1
with only english words, if you want to replace the original column you can save the output in DF1$Text
.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…