In the past people can not get proper material which has high enough eo coefficient, so we seldom heard about VOAs based on eo material.

过去由于受材料的限制，无法找到足够高电光系数的透光材料，所以基于电光材料制造的光器件鲜有耳闻。

youdao

"If you think even with a quarter of a million parishes that still means you've got four or five thousand self-identified Catholics on average per parish, and that's far more than you could fit in church over the course of a week, " says Voas.

BBC: How do you count Catholics?