In Vietnamese I don't think there's a direct equivalent of to be in English, but there are some words to describe the meanings like @bytebuster said:

1. an object x is a part of set X: là, e.g. "đây là quả táo" (this is an apple);
2. an object x has property of y: thì, e.g. "cái hộp thì đỏ" (the box is red)
3. located at: ở, e.g. "tôi đang ở văn phòng" (I am at the office);
4. to mean, e.g. yêu là chết trong lòng một ít (a sentence in the famoust poem by Xuân Diệu) which can roughly be translated as "to love is to die a little in the heart";

However "thì" may not be used very often, instead they are dropped completely, for example "cái bánh này ngọt" - the cake is sweet, or "trời lạnh" - it's cold, esp. when going with exclamation words like "em đẹp lắm" - you're so beautiful!

In Vietnamese I don't think there's a direct equivalent of to be in English, but there are some words to describe the meanings like @bytebuster said:

1. an object x is a part of set X: là, e.g. "đây là quả táo" (this is an apple);
2. an object x has property of y: thì, e.g. "cái hộp thì đỏ" (the box is red)
3. located at: ở, e.g. "tôi đang ở văn phòng" (I am at the office);
4. to mean, e.g. yêu là chết trong lòng một ít (a sentence in the famoust poem by Xuân Diệu) which can roughly be translated as "to love is to die a little bit in the heart";

However "thì" may not be used very often, instead they are dropped completely, for example "cái bánh này ngọt" - the cake is sweet, or "trời lạnh" - it's cold, esp. when going with exclamation words like "em đẹp lắm" - you're so beautiful!