虽说你是一边展示一边讲解，在讲话的过程中，或者回答问题时难免不会用到各种时态变化。因为不清楚你是展示单一产品还是一系列的产品，无法明确地给你帮助。下面提供你几个可能发生的场景，用来表达的方式各异，时态也不同：

Here

we

have

a

product

that

...

Here

is

a

product

that

we

designed

with

...

Now

we're

looking

at

a

product

that

is

...

We'll

take

a

break

now

and

answer

a

few

question.

When

we

come

back,

we

will

be

looking

at

the

next

item

...

Our

designer

spent

XX

months

to

come

up

with

this

new

style.

So

far,

we've

demonstrated

that

...

即便是一个人独白，在讲解说明的过程中都难免会用到各种时态，更不消说如果在和客户口语交流了。因此在我认为不能拘泥于语法，视需要做出相应的变化为宜。