English as a Second Language/Sequence of tenses

Advertisement


Question
Dear Shannon,

Please note the following sentences:

"Galen studied how blood moves round the body." (studied: past; moves: present. Here, I checked a grammar book which says that we can use a present tense to express a fact. But what if I say "moved" instead of "moves, will it stop expressing a fact?

He said, "If I make a mistake, there could be an explosion." (make: present; could: past). Why "could" and not "can"?

Best regards,
Antoine Ghannoum

Answer
1. I think that would be ok, but typically the idea is that blood still moves around people's bodies, so it is something that happens in the present, too.  Now if the fact happened in the past (The forensic specialist examined how the victim was shot), you would use the past tense in all cases.

2. It expresses possibility, not ability.  http://www.onestopenglish.com/support/ask-the-experts/grammar-questions/grammar-

English as a Second Language

All Answers


Answers by Expert:


Ask Experts

Volunteer


Shannon Cole

Expertise

I can answer questions related to learning the English and Spanish language.

Experience

I have taught ESL and Spanish since 1998 at the university and middle school levels. I am a native of the U.S., and have taught in both the U.S. and Mexico.

Organizations
I am owner and operator of www.coleinstitute.com, an online language school.

Publications
Georgia TESOL in Action (1999)

Education/Credentials
B.A. in Spanish; M.Ed. in Language Education

Past/Present Clients
I have clients worldwide, some who want their documents proofread, and others who take lessons with me through the Internet. Some work at high-profile companies and government organizations. Besides the U.S. and Mexico, my recent students come from South Korea, Switzerland, Turkey, Colombia, Russia, Italy, Paraguay, China, Japan, the Philippines, and Saudi Arabia.

©2016 About.com. All rights reserved.