有關tense問題

你的理解是對的。

另外，用 future tense 來表示展覽的內容是適當的，因為那個展覽是在未來舉行，所以應用 future tense。當然，有些地方可以不用 future tense，例如 Jacky Cheung will be singing many songs at the exhibition.，這裡用 future continuous tense 能更生動地表達 Jacky Cheung 唱歌的表演，因為 future continuous tense 強調「唱歌的過程」，而 future tense 則強調「唱歌整件事本身」。

最後那句的 tense 也是對的。你這句是 Type 1 Conditional，在這個情景裏用是合適的，因為它是用來表示「可能性」。而 Type 1 Conditional 中，if 後面的部分是用 present tense，表示後果的那部分則會用 future tense 或 modal verbs（如 may、might、can 等等）。

希望幫到你。

Dear Mary,

We are going to hold a picture exhibition on the next Saturday which is start from 2:30p.m. Lots of different kinds of Chinese Picutres will be show in this
exhibition. Also, we have invited Jacky Cheung be our guest and he will sing
many songs for celebrate the exhibition.Finally,there will be a lucky draw in the end of the exhibition so the vistors can have a chance to receive prizes.
If you are interested ,please contact me at xxxxxxxxx for tickets .

Yours,
Steven

We are holding a picture exhibition at 2:30pm on the coming Saturday. ~ OK

現在進行時 (present continuous) 表示將來, 常含有”意圖”,”安排”或”打算”含義, 並且與表將來的時間狀語連用 (on the coming Saturday)

Dear Mary,

We have an exhibition this Saturday at 2.30pm. There will be a large collection of Chinese art at the exhibition and will feature a lucky draw as well as performance by Jacky Cheung . If you are interested in attending, please contact me at xxxxxxxxx for tickets.


Kind Regards,
Steven

多謝你解答我問題。咁你認為第一句之後用將來式岩唔岩。

Sometimes present continuous tense is used to express future event.